Question

When animals and plants are rotten in absence of air, there produces a gas called

Answer 1

methane
chemical formula :- CH4

Answer 2

Answer:

When animals and plants die and rot and decay- that is when they start the process of decomposition in the lack of oxygen, it is known as “anaerobic decomposition of fermentation”. During this breakdown of organic matter without $O_2$, gasses such as odours of hydrogen sulphide and other sulphide containing compounds like “mercaptans” release.  Organisms which use nitrogen, phosphorus to breakdown a by product of which is $CO_2$ in the reduction process.